Phasing of Zn Application on Yield, Sustainability Index and Soil Zn Fractions Under a Rice-Rice Cropping System Grown in an Inceptisols

Abstract

ABSTRACT Presence of Zn deficiency in soils and its subsequent management forms the basis of the present investigation. To find out the optimum dose and frequency of Zn application a field experiment was conducted by taking fou graded doses of Zn applied in phasing through three frequencies upto 5 year to a rice-rice cropping system grown in an Inceptisols of central farm,OUAT,Bhubaneswar,Odisha. Zinc fractionation study was conducted in initial and post harvest soil to address the possible fate of Zn application on various Zn pools and on yield of rice – rice cropping system. Results after five cropping cycles revealed that rice crop responded to Zn application both to increasing dose and frequency of Zn by producing highest mean grain yield of 4.3 t/ha as well as cumulative yield of 21.3 t/ha in the treatment of every year Zn application @ 5 kg/ha with highest gross return of 1.33 per rupee investment. Highest response of 37% over no Zn application was observed in the same treatment. Among the soil Zn pools affected by Zn application was organic and amorphous oxide bound forms. Residual fraction constituted the highest percent of total Zn among all fractions. Nominal increase in DTPA extractable Zn in post harvest soil under every year Zn application was noticed. Hence for rice growing lowland soils of Odisha application of small dose Zn@ 5 kg/ha every year to the first crop of a rice-rice cropping system can produce a sustainable yield upto 5 year without any adverse effect on soil.